ann_id	IN:	Annotation identifier returned by ANcreate, ANcreatef, or ANselect
	ann	IN:	Text to be written to the annotation
	ann_length	IN:	Length of the annotation text

	Purpose	Writes an annotation.
	Return value	Returns SUCCEED (or 0) if successful and FAIL (or -1) otherwise.
	Description	ANwriteann writes the annotation text provided in the parameter ann to the annotation specified by the parameter ann_id. The parameter ann_length specifies the number of characters in the annotation text.
		If the annotation has already been written with text, ANwriteann will overwrite the current text.

	FORTRAN	integer function afwriteann(ann_id, ann, ann_length)
		integer ann_id, ann_length
		character*(*) ann